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Speciation of heavy metals in bottom sediments defines their ecotoxicity and mobility and therefore needs to be studied thoroughly. Usually single and sequential extraction techniques are used to determine water-soluble, exchangeable, specifically sorbed and carbonates, bound to organic matter, bound to Fe and Mn hydroxides and residual forms. Bottom sediments of the Vyshnevolotsky reservoir (the Upper Volga, the Central region of Russia) were chosen for the research. Lithological and mineral composition of sample...

Situated in the central part of the country, Chott El Jerid is the largest periodic lake in Tunisia. The depression is a flat plain lined with Holocene lacustrine sediments, which mostly developed in the form of alluvia and evaporites. Geochemical properties of sediments were tested using the following methods: FUS-ICP, TD-ICP, INAA, Cold Vapour FIMS. As concerns the basic composition, the following substances were identified (average levels): loss on ignition (LOI) ? 24.27%, SiO2 ? 21.46%, CaO ? 20.54%, Na2O ? 5....

The rivers of the Northern part of European territory of Russia (ETR) contain large amounts of organic matter. This is due to natural features of the area (short cool summer, high wetlands, large areas of forests and features of soil formation), and to specificity of the anthropogenic impact. One of the largest rivers of the Northern ETR is the Northern Dvina River, flowing into the Dvina Bay of the White Sea. A general study of the organic carbon content in the bottom sediment of the Northern Dvina River mouth ar...

It is rather difficult to apply thermodynamic simulation in the forecast of heavy metals migration in aquatic ecosystems due to the fact that the composition of bottom sediments in reservoirs is very changeable and uncertain. An alternative approach is proposed for solving similar problems based on the use of empirical information on heavy metal speciation in bottom sediments. This type of information can be obtained using sequential extraction scheme (for example Tessier scheme). Based on these data, effective th...

The results of Chembursky lake, Vityazevsky, Kiziltashsky and Bugazsky coastal salt lakes expeditionary research are observed, aimed to examine the allocation of methane and sulfur sulfide (total sulfide) according to the vertical cut of bottom sediments (sulfidic muds), and also the value of Eh and pH. pH and Eh values in the examined horizons of coastal salt lakes bottom sediments vary correspondingly in the limits from 7.33?8.06 and -198?-2.5 mV, in the Chembursky lake sediments ? 7.47?7.64 ? -78?+46 mV. CH4 an...

The concern about the environmental contamination by 241Am is caused by the fact, that its half-life period is longer and its mobility is much higher than that of parent plutonium. That is why in soils and sediments the specific activity of the radionuclide increases over time. The alpha-decay energy of 241Am and the relatively short lifetime of the isotope create high specific radioactivity and thermal yield. In bottom sediments, the ratio of 241Am to 241Pu increases every year. All these factors result in a high...

The results of methane and total hydrogen sulphide detection in bottom sediments of small rivers as well as fresh and slightly saline water bodies of the Eastern Donbass are presented. The content of CH4 in sediments of water bodies of Eastern Donbass varies between 0.04-26.8 ?g/g wet mass (w.m.), ?H2S content varies from to less 0.005 than 4.02 mg/g w.m. The maximum concentrations of methane were recorded in the bottom sediments of the Glubokaya River (Station No. 7), while the maximum of the content ?H2S is conf...

The article presents the results of geoecological studies of system of human-made lakes Golubye Ozyora, which are located near the Kaliningrad city. The studies were carried out from 2009 to 2016 in the framework of studying of the regional specific features of the formation of geochemical background of water bodies and the impact of the cross-media pollutions. It was in studies revealed the general characterization of lake-bottom sediments and water including the grain-size measurements; the determination of the ...